OK I did this wrong cuz I am having trouble understanding the entire WTF, my SF and F should be:

SF
Nadal def. Murray
Federer def. Djokovic

F
Nadal def. Federer

I don't know if this is right either. Maybe I'm just too stupid for this game.

The players who finish #1 in each group has to play the #2 from the opposite group in the SF. This is why we have to predict who will finish #1 and #2 in both groups - so we can then predict the SF and F matches. Snoo Foo, based on your predictions in your original post, the SF match-ups in your revised post I quoted above are correct.